The present disclosure relates to power amplifier circuits. Mobile communication devices such as cellular phones and the like use a power amplifier circuit to amplify power of a signal to be transmitted to a base station. Recently, in cellular phones, modulation techniques such as High Speed Uplink Packet Access (HSUPA), Long Term Evolution (LTE), LTE-Advanced, and the like, which are standards for high speed data communication, have been used. In such communication standards, it is important to reduce deviation in phase or amplitude to improve communication speeds. In other words, higher linearity is desirable in power amplifier circuits. Further, in such communication standards, a range (dynamic range) across which the amplitude of a signal varies becomes wider in many cases in order to improve the communication speed. To increase the linearity even in the case with a wider dynamic range, a higher power supply voltage is desirable, and this tends to cause higher power consumption at the power amplifier circuit.
On the other hand, in cellular phones, to extend operation time for call or communication, it is desirable to reduce power consumption. For example, Japanese Unexamined Patent Application Publication No. 2012-4821 discloses an envelope tracking technique in which improvement of power efficiency is achieved by controlling a power supply voltage of a power amplifier circuit as a function of an amplitude level of an input radio frequency (RF) signal.